Hi, Kevin, and welcome to the wonderfully, happily insane world of ZBrush. 
Youâve encountered what should probably be called âNewbie Question Number One,â and the answer lies in just what makes ZBrush so unique.
ZBrush is a 2.5D paint program. In other words, it paints on a two dimensional plane, but it does so using depth information. In order to accomplish this, it combines paint and effects brushes such as you might find in other apps with 3D modeling capabilities and then throws in some unique 3D brushes just to make life interesting.
The way that it pulls all of this off is that it allows you to model 3D shapes from primitives (or by importing OBJ or DXF files). You can model and manipulate these models to your heartâs content in a way that is much like working with clay. You can also use deformation masks, alpha masks, progression masks, transparencies and a whole slew of other tricks to really accomplish some neat stuff with your model. When youâre happy with it, youâre then faced with two options: you can export it for use in another program, or you can âsnapshotâ one or more instances of it to your canvas (I use the term âinstanceâ because the original remains in your Tool palette while a copy of it is made on the canvas â kind of like Flash and similar programs).
Now hereâs where you ran into your surprise. When you snapshot it to the canvas (by leaving Edit Mode, clicking the snapshot button, or selecting another brush/tool), you fix it in 3D space. Permanently. At this point, it goes from being a true 3D object to being a 2.5D object. In other words, it still retains all of the depth information that made it a 3D object, but its point of view is now permanently fixed to the cameraâs angle. This allows you to now start acting upon it using other tools.
So to answer your first question, âWhat can ZBrush do?â I would have to say that it is primarily used to create 3D scenes from a single, fixed POV. These scenes use materials, textures, lighting effects, depth cueing and all sorts of other stuff that you see in other 3D programs (many of them much more expensive). But they are output as single, 2D images. The result is paintings that have a remarkable sense of realism.
I said âprimarilyâ in that last paragraph because Iâm not sure that weâll ever stop figuring out new ways to use the program. Some people use it just for 2.5D painting. Others never even touch the 3D tools, and stictly use the brushes â but paint with materials rather than just color. Others model with it for export to other programs. Still others use it to texture models for use in other programs. Some people paint directly on the model in edit mode, while others paint on the unwrapped texture with 3D brushes, then wrap it back onto the model for textures with dramatic depth. The list goes on.
Unfortunately, this also means that itâs kind of easy for the beginner to get lost in the program, wondering where to begin. Go to the QuickLinks section via the link at the top of this page. There you will find a slew of tutorials and threads where other people have asked questions similar to yours and received answers from more experienced users. Also, check out the ZScripts that came with ZBrush. Open your ZScript palette, click on the Load button. I recommend starting with the ZBrush Picnic, since it takes you through the construction of an entire scene in a way that shows you some of the true power of the program and how the various elements work together. Then use the Primers to get more specific info on individual items.
Hope all of that helps, and answers some of your questions satisfactorily. And never be shy about asking questions in here â ZBCentral is one of your best resources thanks to the QuickLinks and the very helpful group of members.
Cheers!